What’s in a name: Evolution of terminology




  • 1970s: “Inadvertent Climate Modification” (NAS, 1971)


  • 1980s–1990s: “Global Warming”


  • 2000s: “Climate Change”


  • Present: “Global Change” – includes climate change, land use, biodiversity, pollution, etc.

What’s in a name: What is Global Change Biology?




  • Study of how global environmental changes affect biological systems


  • Includes: climate change, land transformation, nutrient cycles, pollution, species introductions


  • Focus on human-driven causes
    • human impacts on the biosphere have ramped up at key times in our history

What’s in a name: Anthropocene



  • Current period where human activities are the dominant force shaping the Earth’s geology and ecosystems
    • appears in scientific and social discourse


  • Denotes current geological age - YET not an officially recognized geological epoch
    • coincides with Atomic-Age (post 1950)
    • Crawford lake (Canada) selected as ‘golden spike’


  • Proposal rejected in 2024 after 15 years of deliberation
    • not enough data and not enough time has passes since start date

Key drivers of global change and their consequences



  • Climate change


  • Land transformation


  • Disruption of biogeochemical cycles


  • Pollution


  • Introduction of species outside their native ranges

Key drivers: Climate Change – Causes


  • Greenhouse gas emissions (GHG’s)
    • Carbon dioxide (CO2) from industry/transportation/energy production
    • Methane (CH4) from agriculture/landfills/fossil fuels
    • Nitrous Oxide (N20) from agriculture/industry
    • Water vapor (H20) from evaporation
  • Deforestation - plants naturally take up (CO2)


  • Shifts in albedo (color = reflective) from urbanization


  • Non-human influences - Solar variability, volcanic activity, and ocean currents

Earth’s Temperature is a Balancing Act


The Greenhouse Gas Effect is a natural process


GHG’s play a critical role in maintaining Earth’s habitable temperature. Without GHG’s, Earth would likely plunge into an ice age, as heat would escape back into space.

Human have Modified the Existing Greenhouse Gas Effect


Climate Change – Effects on Natural Systems





  • Species distribution shifts


  • Migration and breeding changes


  • Coral bleaching, ocean acidification


  • Extinctions

Climate Change – Effects on Our Species


Land Transformation by Humans is a Global Phenonmenon


  • Agriculture: Conversion of forests, grasslands, and wetlands into croplands and pastures


  • Urbanization: Expansion of cities, roads, and infrastructure fragments natural habitats
    • Increases impervious surfaces, disrupting water flow, urban heat islands, and pollution


  • Deforestation: Logging for timber, agriculture, and fuel
    • removes carbon sinks, causes soil erosion, and loss of biodiversity


  • Infrastructure Development: Construction of dams, highways, and mining operations
    • modifies/removes habitats, interrupts animal migration routes and river flows.


  • Land Drainage: Conversion of wetlands, estuaries, and mangroves for development
    • Loss of ecosystems that buffer storms and filter pollutants.

Land Transformation: Habitat Loss


Land Transformation: Biodiversity


Land Transformation: Altered Water Flows


Land Transformation: Expansion of Human-Wildland Interface


Land Transformation: Removal of Historic Fire Regimes


Land Transformation: Creation of Urban Heat Islands


Altered Biogeochemical Cycles – Overview


  • Biogeochemical cycle: the movement and transformation of chemical elements/compounds between living organisms, the atmosphere, and the Earth’s crust


  • Carbon Cycle - C is main element for building organic molecules essential for life
    • Fossil Fuel Combustion: Releases vast amounts of COâ‚‚
    • Deforestation: Reduces the Earth’s capacity to absorb atmospheric carbon


  • Nitrogen Cycle - N is used to build molecules like proteins, nucleic acids (DNA and RNA)
    • Synthetic Fertilizer: Adds nitrogen to soils and waterways, which escapes into aquatic ecosystems
    • Fossil Fuel Combustion: Produces greenhouse gasses, contributes to smog, and acid rain,
    • Livestock Waste: Releases greenhouse gasses


  • Phosphorus Cycle - building blocks like DNA and RNA, energy molecules, cell membranes
    • Agricultural Runoff: Excess phosphorus from fertilizers enters rivers and lakes
    • Wastewater Discharge: Human sewage contributes to phosphorus overload in aquatic systems

Eutrophication - Excessive N & P in Aquatic Systems


Excessive nutrient levels lead to rapid algal growth. As these algal blooms decay, oxygen is depleted in the water, suffocating fish and other organisms

Ocean Acidification from CO2 emissions


Oceans absorb CO2. When CO2 dissolves in seawater, it forms carbonic acid, releasing hydrogen ions and increases ocean acidity. More acidification makes it harder for organisms to build/maintain shells

Pollution from Humans is Vast



  • Industrial Activities (factories) emit air pollutants
    • Chemical waste and heavy metals often contaminate soil and water.
    • Plastic manufacturing also contributes to microplastic pollution.


  • Vehicles release GHG’s, volatile organic compounds (VOCs), and particulate matter
    • land and air transportation


  • Agriculture fertilizer, pesticides and herbicides contaminate soil and water
    • harming non-target organisms


  • Residential and Urban Waste includes household chemicals, plastic, and electronic waste
    • dssege and wastewater discharge pollutes aquatic ecosystems


  • Plastic waste, oil spills, and ballast water discharge pollute oceans and harm marine life

Biological Effects of Pollution





  • Reproductive decline


  • Genetic mutations


  • Ecosystem degradation


  • Bioaccumulation

Species Introductions – Why?


  • An introduced species is a species that has been brough by human activity to an area where it does not naturally occur


  • If specices becomes harmful to the environment = invasive


  • Intentional: agriculture, pets
    • many crop species = non-native
    • species are sometimes introduced to fight an invasice species = biocontrol


  • Unintentional: ballast water, trade


  • Accelerated by globalization

Invasive Species – Impacts


Invasive species often lack natural predators/diseases in new locations, allowing them to grow rapidly and outcome native species

Global Change Factors can be Interconnected


Global Change Factors can be Interconnected – Coral Reefs






When corals becomes stressed, the zooxanthellae (colorful algae) leave, causing coral bleaching and potentially death of the corals


What causes corals to be stressed?